Ninety-nine Tükuna Indians, inhabitants of the high Amazon, were typed for the HLA antigens. The method used was the microlymphocytotoxicity technique recommended by the NIH. At the same time, cross-matching was performed between the lymphocytes of the 99 Indians and the sera of 240 other multiparous Indians. Later the multiparous sera were cross-matched with a selected panel of Caucasoid individuals. The results showed that the most frequent antigens for th HLA-A locus were A2, Aw24 and Aw31. As for the HLA-B locus, B5, Bw39 and B40 were most frequent. The haplotypes HLA-Aw31-Bw39, and A2-B5 were in linkage disequilibrium. The results of the cross-matching showed 21.3% sera with positive reactions against Indian cells. Ten sera presented antibodies against known HLA antigens; five of them were monospecific, four had two specificities, and one showed three specificities. It was not possible to arrive at any conclusion about the 41 remaining sera. Six sera had positive reactions only with Indians cells.